The present invention relates to a DNA containing a cDNA segment coding for a human vasoconstrictive peptide (SEQ ID NO:1), namely human endothein-2, a precursor protein of human endothelin-2 (SEQ ID NO:2) and a method for preparing endothelin-2.
In this specification, the term xe2x80x9cprecursor proteinxe2x80x9d is preferably used to describe a protein which includes an amino acid sequence of a mature peptide and has a portion or all of an amino acid sequence coded with a DNA segment of the peptide at the N-terminus, the C-terminus or both termini thereof.
There have been reports of endothelium-dependent vasoconstrictor reactions to various mechanical and chemical stimuli as well as endothelium-dependent vasodilative reactions. For example, it is known that vasoconstriction can be induced by mechanical loads such as vascular stretch and increased vascular inner pressure, by such agents as thrombin and by hypoxemia, and further that noradrenaline-induced vasoconstriction can be enhanced by use of neuropeptide Y [Proc. Natl. Acad. Sci. U.S.A. 79, 5485 (1982); ibid. 81, 4577 (1984)].
Endothelial cell-derived coronary vascular constrictor factors (each having molecular weights of 8,500 and 3,000) are described in Amer. J. Physiol. 248, c550 (1985) and J. Cell Physiol. 132, 263 (1987). However, their sequences are unknown. An endothelial cell-derived peptide-like substance is also described in J. Pharmacl. Exp. Ther. 236, 339 (1985). However, the sequence of that substance is also unknown.
On the other hand, vasopressin is known as a peptide having a vasoconstrictor activity. The amino acid sequence of vasopression has been determined. There have been no reports, however, that vasopressin was obtained from mammalian or bird vascular endothelial cells. Although there is a report that an angiotensin having a vasoconstrictor activity was obtained from the endothelial cells of bovine aortas [Circulation Research 60, 422 (1987)], the angiotensin is a peptide having a molecular weight of only about 1,000.
Some of the present inventors have previously succeeded in isolating porcine endothelin as a peptide having a similar vasoconstrictor activity from the endothelial cells of porcine aortas (Japanese Patent Application No. 255381/1987). Some of the present inventors have also succeeded in isolating human endothelin and cloning porcine endothelin cDNA and human endothelin cDNA (Japanese Patent Application Nos. 275613/1987, 313155/1987 and 148158/1988). The mature polypeptides of the porcine endothelin and the human endothelin have the same amino acid sequence, and are referred to as endothelin-1.
Further, the present inventors have filed patent applications with respect to the isolation of rat endothelin and the cloning of its cDNA (Japanese Patent Application Nos. 174935/1988 and 188083/1988), and this is referred to as endothelin-3.
Furthermore, the present inventors have also filed a patent application with respect to the cloning of human endothelin-3 (Japanese Patent Application No. 278497/1989).
Moreover, the present inventors have also filed a patent application with respect to the isolation of mouse endothelin and the cloning of its cDNA (Japanese Patent Application No. 223389/1988), and this is referred to as endothelin B.
In addition, the present inventors have cloned, from a genomic human library, a DNA coding for endothelin having an amino acid sequence different from that of endothelin-1 which has been named endothelin-2, and have filed a patent application with respect to a protein of endothelin-2 and its DNA (Japanese Patent Application No. 274990/1989).
The amino acid sequences of these endothelin-1 (SEQ ID NO:3), endothelin B (SEQ ID NO:4), endothelin-3 (SEQ ID NO:5) and endothelin-2 (SEQ ID NO:6) are shown in FIG. 1 in comparison to one another.
Endothelin is a general term for peptides having a molecular weight of 2500xc2x1300 and having 21 amino acid residues, including four cysteine groups located at the 1st, 3rd, 11th and 15th residues from the N-terminus of the amino acid sequence, which form two sets of disulfide bonds. One of the combinations of the disulfide bonds may be 1-15 and 3-11 cysteine groups, and the other may be 1-11 and 3-15. The former combination is higher in ratio of formation and in activity. than the latter combination.
As described above, homologous endothelin peptides have been discovered from various animals. However, no novel homologous genes have been discovered from the same animal species. It is therefore a current subject that novel homologous endothelin is further screened, and the structure and activity of the endothelin are studied, thereby examining its usefulness, and that the novel peptide is cloned by recombinant DNA technology to allow mass production thereof.
The present inventors have variously studied, considering that important contributions will be made to future studies and medical treatments, if a novel homologous gene having the vasoconstrictor activity described above can be isolated and further prepared by recombinant DNA technology. As a result, the following information has been obtained, thus arriving at the present invention.
Namely, the present inventors have succeeded in cloning cDNA (complementary DNA) coding for endothelin having an amino acid sequence different from those of the above endothelin-1 and endothelin-3 [human endothelin (endothelin A) and endothelin-3] from a human cDNA library by using as a probe the synthesized DNA segment coding for a portion of genomic DNA of the human endothelin described in the patent applications previously filed and a DNA comprising an about 99-bp genomic DNA segment of endothelin-2, and consequently in pioneering its mass production by recombinant technology. The present inventors further provide a precursor of human endothelin-2 having a novel amino acid sequence.
In accordance with the present invention, there are provided (1) a DNA containing a cDNA segment coding for human endothelin-2, (2) a precursor of human endothelin-2, (3) a transformant carrying a DNA containing a cDNA segment coding for human endothelin-2, and (4) a method for preparing mature human endothelin-2 which comprises culturing the transformant described in (3), accumulating a protein in a culture medium, and collecting the same.